A weakened guardrail mounting connection

ABSTRACT

In accordance with a particular embodiment of the present invention, a guardrail safety system includes a guardrail beam and a plurality of support posts in spaced apart relation to one another. Each support post is configured to be releasably coupled to the guardrail beam. A plurality of connectors couple the plurality of support posts to the guardrail beam. Each connector includes a head portion that is configured to provide a sufficiently strong connection between the guardrail beam and the support post to support the guardrail beam and a sufficiently weak connection between the guardrail beam and the support post to enable the support post to detach from the guardrail beam when struck by the errant vehicle.

RELATED APPLICATION

This patent application claims priority from Patent Application Ser. No.60/718,679, filed Sep. 19, 2005, entitled A Weakened Guardrail MountingConnection, attorney docket no. 017575.1083.

TECHNICAL FIELD

The present invention relates generally to guardrail systems and moreparticularly, to a weakened guardrail mounting connection.

BACKGROUND

Guardrail systems are widely used along heavily traveled roadways toenhance the safety of the roadway and adjacent roadside. Guardrail beamsand their corresponding support posts are employed to accomplishmultiple tasks. Upon vehicle impact, a guardrail acts to contain andredirect the errant vehicle.

For many years, standard heavy gauge metal guardrails known as “W-beams”have been used on the nation's roadways to accomplish these tasks andothers. Named after its characteristic shape, the “W-beam” is typicallyanchored to the ground using support posts made of metal, wood, or acombination of both. A terminal post is used at or near the terminal endof the guardrail system. Support posts other than the terminal posts aretermed “length-of-need” (LON) posts. LON posts support the W-beam alongthe intermediary portion of the guardrail system between opposingterminal ends of the guardrail system.

Wood support posts may be more readily available and more economicalthan metal posts in some geographical areas. In other areas, metal(e.g., steel) posts may be more readily available and more economicaland may be preferred for their ease of installation using drivingmethods. As an additional benefit, wood support posts used in a LON orterminal portion of a guardrail system have been made to break away uponimpact, thus producing a desired behavior during a collision by avehicle at the impact site. However, in some environments, wood postsdeteriorate more rapidly and alternate materials are sought.

Commonly used steel posts do not break away in the desired fashion andare not optimal for use in the guardrail system and especially notsuitable for use in the terminal section of a guardrail system. Breakaway steel support posts that are modified to allow for failure during acollision have recently become available. Examples include a “hingedbreakaway post” and the “energy absorbing breakaway steel guardrailpost” described in U.S. Pat. No. 6,254,063. Many such prior attemptsrequire substantial time, money, and resources during fabrication,modification, and/or installation.

SUMMARY

In accordance with a particular embodiment of the present invention, aguardrail safety system includes a guardrail beam and a plurality ofsupport posts in spaced apart relation to one another. Each support postis configured to be releasably coupled to the guardrail beam. Aplurality of connectors couple the plurality of support posts to theguardrail beam. Each connector includes a head portion that isconfigured to provide a sufficiently strong connection between theguardrail beam and the support post to support the guardrail beam and asufficiently weak connection between the guardrail beam and the supportpost to enable the support post to detach from the guardrail beam whenstruck by the errant vehicle.

Technical advantages of particular embodiments of the present inventioninclude a guardrail support post that has sufficient strength toredirect vehicles that collide along the length of the guardrail systemat an angle to the flow of traffic. As a result, the guardrail systemmay fail in a designed manner even at a low level of tension.

A further technical advantage of particular embodiments of the presentinvention may include a weakened connection between the support post andguardrail beam such that the support post detaches from the guardrailbeam when struck by an errant vehicle. Specifically, a connector may beprovided that adequately supports the guardrail beam while releasingfrom the guardrail beam when a lateral force is applied to the guardrailbeam. Accordingly, in particular embodiments, an advantage may be thatthe connection is strong in shear and weak in tension.

Other technical advantages will be readily apparent to one skilled inthe art from the following figures, descriptions and claims. Moreover,while specific advantages have been enumerated above, variousembodiments may include all, some, or none of the enumerated advantages.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention and theadvantages thereof, reference is now made to the following briefdescriptions, taken in conjunction with the accompanying drawings anddetailed description, wherein like reference numerals represent likeparts, in which:

FIG. 1 illustrates a side view of a guardrail safety system thatincorporates certain aspects of the present invention;

FIGS. 2A-2C illustrate a guardrail support post suitable for use withthe guardrail system of FIG. 1, in accordance with a particularembodiment of the present invention;

FIGS. 3A-3C illustrate another guardrail support post suitable for usewith the guardrail system of FIG. 1, in accordance with anotherembodiment of the present invention;

FIGS. 4A-4C illustrate a LON guardrail support post suitable for usewith the guardrail system of FIG. 1, in accordance with a particularembodiment of the present invention;

FIGS. 5A-5C illustrate another LON guardrail support post suitable foruse with the guardrail system of FIG. 1, in accordance with anotherembodiment of the present invention;

FIGS. 6A-6C illustrate another LON guardrail support post suitable foruse with the guardrail system of FIG. 1, in accordance with anotherembodiment of the present invention;

FIG. 7 illustrates a support post that includes a modified flange forthe protection of a guardrail beam, in accordance with one embodiment ofthe present invention;

FIGS. 8A and 8B illustrates a flange protector for attachment to asupport post for the protection of a guardrail beam, in accordance withone embodiment of the present invention;

FIG. 9 illustrates a connector for coupling a guardrail beam with asupport post, in accordance with a particular embodiment of the presentinvention; and

FIGS. 10A-10C illustrate a connector for coupling a guardrail beam witha support post, in accordance with an alternative embodiment of thepresent invention.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

FIG. 1 illustrates a guardrail safety system 10 that incorporatescertain aspects of the present invention. Guardrail system 10 may beinstalled adjacent a roadway to protect vehicles, drivers, andpassengers from various obstacles and hazards and prevent vehicles fromleaving the roadway during a traffic accident or other hazardouscondition. Guardrail systems that incorporate certain aspects of thepresent invention may be used in median strips or shoulders of highways,roadways, or any path that is likely to encounter vehicular traffic.Guardrail system 10 includes a guardrail beam 12 and support posts 14that anchor guardrail beam 12 in place along the roadway. Asillustrated, guardrail system 10 includes three sections. Two terminalsections 16 are located on opposing ends of guardrail system 10 and areseparated by an intermediary length-of-need (LON) section 18.

Support posts 14 have been modified to decrease the strength of supportposts 14 in a direction generally parallel to axis 20 (generally alongthe direction of traffic) without substantially decreasing its strengthin a direction generally perpendicular to axis 20 (out of the page inFIG. 1). Stated differently, support posts 14 exhibit adequate strengthin the lateral direction but sufficiently low strength in thelongitudinal direction. Accordingly, if a vehicle impacts guardrailsystem 10 “head-on” adjacent an end terminal post 22, support posts 14will tend to yield (e.g., buckle), while allowing the vehicle todecelerate as it impacts consecutive support posts 14. However, if avehicle strikes guardrail system 10 along the face of and at an angle toguardrail beam 12, support posts 14 will provide sufficient resistance(strength) to redirect the vehicle along a path generally parallel withguardrail beam 12.

Guardrail system 10 is intended to keep errant vehicles from leaving theroadway during a crash or other hazardous situation. In many instances,guardrail 10 is installed between a roadway and a significant hazard tovehicles (e.g., another roadway, a bridge, cliff, etc.). Therefore,guardrail system 10 should be designed to withstand a significant impactfrom a direction that forms an angle to the roadway without substantialfailure. It is this lateral strength that allows guardrail system 10 towithstand the impact and still redirect the vehicle so that it is onceagain traveling generally in the direction of the roadway.

Testing and experience have continuously shown, however, that guardrailsystems may actually introduce additional hazards to the roadway andsurrounding areas. This is particularly true with respect to vehiclesthat impact the guardrail system adjacent its terminal section 16 in adirection generally parallel to the roadway. For example, if theguardrail system were rigidly fixed in place during a crash, seriousinjury and damage may result to the errant vehicle, its driver, andpassengers. Accordingly, many attempts have been made to minimize thisadded risk. Such methods generally include the use of terminal portionsthat are tapered from the ground up to effectively reduce the impact ofhead on collisions and to create a ramp-like effect that causes vehiclesto go airborne during a crash. Other methods include breakaway cableterminals (BCT), vehicle attenuating terminals (VAT), SENTRE endtreatments, breakaway end terminals (BET) and the breakaway supportposts of U.S. Pat. No. 6,398,192 (“'192 Patent”). Many such terminals,supports, end treatments and the like are commercially available fromvarious organizations. Examples include the HBA post by ExodyneTechnologies and Trinity Industries and a breakaway support post similarin configuration to that described in the '192 Patent.

Improperly designed posts in the LON portion of a guardrail system mayalso introduce additional hazards to the roadway and surrounding areas.This is particularly true with respect to vehicles that impact the LONportion of the guardrail system at a substantial angle to the guardrailbeam. In such a scenario, snagging or contact between the vehicle andposts can cause severe vehicle damage, deformation to the occupantcompartment, high vehicle decelerations, and failure or rupture of theguardrail beam. Additionally, the guardrail may fail in its purposes ofcontaining and redirecting the errant vehicle.

Referring again to FIG. 1, each terminal section 14 includes a terminalportion of guardrail beam 12, one terminal end post 22, and fiveterminal support posts 14 a. LON guardrail support posts 14 b may beused for the balance of guardrail system 10 to support a LON portion ofguardrail beam 12. As will be described in more detail below, it shouldbe recognized that terminal support posts 14 a and LON support posts 14b may be identical or may differ where desired. In particularembodiments, for example, terminal support posts 14 a and LON supportposts 14 b may differ in size and configuration where the terminalsections 16 and LON section 18 are designed for different impactconditions. In other embodiments, terminal support posts 14 a and LONsupport posts 14 b may be identical or substantially identical such thatany support post 14 described herein is suitable for installation at anylocation within guardrail system 10. In such embodiments, terminalsupport posts 14 a and LON support posts 14 b may be interchangeablewithin guardrail system 10.

Support posts 14 may be embedded in the ground, a concrete footing, or ametal socket. Support posts 14 may be made of wood, metal, plastic,composite materials, or any combination of these or other suitablematerials. It is also recognized that each support post 14 withinguardrail system 10 need not necessarily be made of the same material orinclude the same structural features. Furthermore, the cross-section ofsupport posts 14 may be any engineered shape suitable for releasablysupporting guardrail beam 12. Such cross-sectional shapes may include,but are not limited to, square, rectangular, round, elliptical,trapezoidal, solid, hollow, closed, or open.

Although FIG. 1 is illustrated without dimensions, in a particularembodiment, it is understood that guardrail system 10 may be ofdifferent lengths depending on the nature of the roadside hazard beingshielded. Each terminal section 16 may have a length on the order ofapproximately 11.4 meters (37.5 feet), respectively, and LON section 18will have a length that varies as needed. In such an embodiment, supportposts 14 may be placed along guardrail beam 12 at a spacing on the orderof approximately 1.9 meters (6.25 feet) or other distance as required toobtain the desired deflection and impact performance.

In such an embodiment, guardrail beam 12 may include multiple 12-gaugeW-beam rail elements of a length on the order of approximately 3.8meters (12.5 feet) or 7.6 meters (25 feet). The guardrail beam sectionsmay be mounted at a height of 78.74 centimeter (31 inch) with railsplices positioned mid-span between the support posts 14. Whileguardrail beam 12 may include W-beam rail elements, it is generallyrecognized that the illustrated guardrail beam 12 is merely an exampleof a beam that may be used in a guardrail system. Guardrail beams 12 mayinclude conventional W-beam guardrails, thrie beam guardrails, boxbeams, wire ropes, or other structural members suitable for redirectingan errant vehicle upon impact. It is also recognized that theconfiguration and dimensions of any of the above-described elementswithin guardrail system 10 may vary as desired.

FIGS. 2A-2C illustrate a guardrail support post 34, in accordance with aparticular embodiment of the present invention. Support post 34 includesan elongate continuous structural member of a standard Wide flangeconfiguration. Support post 34 includes two flanges 36 and 38 that aregenerally parallel with one another and in a spaced relation. A web 40forms the coupling between flanges 36 and 38. Flanges 36 and 38 includea generally identical configuration of boltholes 48 and cutouts 50,therein.

With regard to a Wide flange shape used as a guardrail post, the crosssection is typically shaped like the letter “H”. The cross section hastwo major axes for bending. The “weak” axis generally refers to acentral axis that extends through the web and is perpendicular to theflanges. The “strong” axis generally refers to a central axis that isperpendicular to the web and parallel to the planes of the flanges. Theweak axis for a conventional installation of guardrail extends generallytransversely to the road. The strong axis extends generally along theroadway.

In the illustrated embodiment of FIGS. 2A-2C, the Wide flange is astandard W6×8.5, which is commonly used in fabricating support posts forguardrail installations. In particular embodiments, the W6×8.5 such asthat illustrated in FIGS. 2A-2C may be particularly well suited forinstallation as a support post 14 a in terminal section 16 of guardrailsystem 10. One advantage of some embodiments is the ability to re-useexisting standard equipment to fabricate, modify, and install supportpost 34 without substantial modification to the equipment. Those ofordinary skill in the art will recognize that wide flange beams may beavailable in many different sizes. For example, a standard W6×8.5 Wideflange may have a nominal six-inch depth and weigh nine pounds per foot.However, a Wide flange having a six-inch depth and weighing eight andone-half pounds per foot may also be referred to as a W6×8.5 Wide flangeand is considered equivalent in the trade. The term “W6×8.5 Wide flange”is intended to refer to all sizes and configurations of guardrail poststhat may be referred to as “W6×8.5” by a person of ordinary skill in theart. In addition, persons skilled in the art recognize other names usedfor wide flanges include but are not limited to “I-beam,” “H-beam,”“W-beam,” “S-beam,” “M-beam,” or the term “shape” may be substituted for“beam.”

Support post 34 includes a relatively “weak” axis W and a relatively“strong” axis S. For the reasons described above, support post 34 isnormally installed along a roadway such that weak axis W is generallyperpendicular to the direction of traffic, and strong axis S isgenerally parallel to the direction of traffic. Accordingly, supportpost 34 is typically able to withstand a significant impact (e.g., witha car traveling at a high rate of speed) about the strong axis S withoutsubstantial failure. However, support post 34 is intentionally designedsuch that yielding will more readily occur in response to an impactabout the weak axis W.

In the illustrated embodiment, support post 34 has a length on the orderof approximately 1,830 mm (6 feet), and it includes an upper portion 42,a lower portion 44, and a mid portion 46 that couples upper portion 42with lower portion 44. Upper portion 42 includes two boltholes 48 ineach of flanges 36 and 38 that are adapted to receive connectors for theinstallation of a guardrail beam (e.g., guardrail beam 12) upon supportpost 34. Lower portion 44 is suitable for installation below grade aspart of a guardrail support system. Mid portion 46 includes two cutouts50 in both flanges 36 and 38, which are configured to further weakensupport post 34 about the weak axis W, to more readily allow foryielding due to impact from a vehicle along that direction. The overalllength of support post 34 and its upper, lower, and mid portions mayvary significantly within the teachings of the present invention.

Bolt holes 48 include a standard configuration that allow for theinstallation of widely used guardrail beams upon support posts 34. Ingeneral, bolt holes 48 align with the center of the guardrail beam andmaintain the center of the guardrail beam at a distance that is between550 and 750 millimeters (1.8-2.5 feet) above grade. In the particularembodiment illustrated, bolt holes 48 maintain the center of theguardrail beam at a distance that is on the order of 550 (1.8 feet)above grade. Bolt holes 48 have a diameter on the order of approximately21 millimeters. However, it is generally recognized that the illustrateddimensions are for example purposes only; the number, size, location andconfiguration of boltholes 48 may be significantly modified within theteachings of the present invention.

Cutouts 50 are positioned within mid portion 46 to weaken support post34 about weak axis W adjacent grade (when installed). This willaccommodate yielding of support post 34 approximately at grade, allowingsupport post 34 to “fold” over from the point of yielding, upward. Sincelower portion 44 is below grade, it is not expected that the ground orlower portion 44 of support post 34 will appreciably deflect during animpact about the weak axis of the post. In the illustrated embodiment ofFIGS. 2A-2C, cutouts 50 are approximately thirteen millimeters indiameter. It is generally recognized, however, that the provideddimensions of cutouts 72 are provided for example purposes only; cutouts72 may be of any appropriate size and may vary between approximately 13and 21 millimeters, in various embodiments.

Since cutouts 50 are intended to occur approximately at grade and thecenter of bolt holes 48 are intended to occur between 550 and 750millimeters (1.8-2.5 feet) above grade, bolt holes 48 occur between 550and 750 millimeters (1.8-2.5 feet) above cutouts 50. In the illustratedembodiment, bolt holes 48 occur at approximately 550 millimeters (1.8feet) above cutouts 50. It will be recognized by those of ordinary skillin the art, however, that the size, configuration, location and numberof bolt holes, cutouts, and their relationship with each other may bevaried significantly within the teachings of the present invention.

Additionally, the location of cutouts 50 may vary in accordance with theteachings of the present invention. The configuration of FIGS. 2A-2Cenvisions that cutouts 50 will occur approximately at grade level. Inother embodiments, cutouts 50 may occur below grade or above grade. Thedepth of cutouts 50 below grade should not exceed an amount that willprevent support post 34 from yielding at or near the location of cutouts50. At some depth below grade, the surrounding earthen (or other)material will reinforce lower portion 44 of support post 34 to an extentthat will no longer accommodate such yielding to occur.

The height of cutouts 50 above grade should not exceed a point at whichsupport post 34 will yield at cutouts 50 and leave a “stub” above gradethat can snag vehicles and otherwise cause excessive injury and/orexcessive damage. Such a stub could be detrimental to the redirectiveeffect of the guardrail system in which support post 34 is operating.

Support post 34 is a single, continuous structural member that does notrequire any labor in field assembly, welding, or special handling. Withthe exception of boltholes 48 and cutouts 50, support post 34 has acontinuous, generally uniform cross-section from top edge 52 to bottomedge 54. Therefore, fabrication of support post 34 is simplified withrespect to other multiple component products. Furthermore, support post34 can be shipped as one piece and installed as one piece. Many priorattempts that included multiple components that were hinged or otherwiseconnected could not be shipped and/or installed as a single unit withoutdamaging the support post.

Similarly, many such prior efforts required specialized equipment forproper installation and often required a significant amount of fieldlabor to perform such installation. In contrast, support post 34 can beinstalled using traditional guardrail post installation equipment (e.g.,guardrail post drivers).

Previous attempts to accommodate failure of a guardrail support posthave often weakened the support post about the strong axis S, whichimpacts the support post's ability to redirect a vehicle that collideswith the support in a direction generally perpendicular to or at anangle to the roadway. For this reason, such support posts may beunacceptable for use along a roadway and may fail to comply withgoverning federal standards bodies' requirements. Patent ApplicationPCT/US98/09029 ('029 Application) illustrates a support post havingslotted openings disposed therein. These slots are substantially longer(vertically) than they are wide (horizontal).

Cutouts 50 of support posts 34 are configured to reduce the strength ofsupport post 34 about weak axis W, without substantially changing thebehavior of the support post 34 about strong axis S. In the illustratedembodiment, cutouts 50 comprise generally circular openings that havebeen punched or drilled through support post 34. Cutouts 50 provide anenhanced ability to control the point of yielding of support post 34during a collision with a vehicle. For example, the support post of the'029 Application may fail at any point along the slots, and failure maybe based upon imperfections in the material adjacent the slots. Bylimiting the vertical dimension of cutout 50, it is easier to dictatethe precise point of failure of support post 34 along its verticallength.

Furthermore, the slots of the '029 Application require the removal of asubstantial amount of material from the flange. This weakens the flangealong directions other than perpendicular to the web. Furthermore,during a dynamic crash situation in which the impact may come from anyangle, twisting or bending of the flange may result in the flangechanging its orientation in response to the initial impact. Accordingly,the support post having vertical slots similar to the '029 Applicationmay fail prematurely along the strong axis and lose its ability toredirect the vehicle.

In accordance with certain example embodiments of the present invention,the vertical dimension of cutout 50 is limited based upon the horizontaldimension of cutout 50. For example, a ratio of the vertical dimensionof any particular cutout may be equal to or less than three times thehorizontal dimension. Alternatively, the ratio may be limited to twotimes the horizontal dimension. In the illustrated embodiment of FIGS.2A-2C, the ratio is 1:1 since cutout 50 is generally a circular openingin the support post. The smaller the vertical dimension of the cutout,the more precisely the designer may dictate the point of yielding alongthe vertical length of support post 34.

Various configurations of cutouts 50 are available to a designer ofsupport post 34, in accordance with the teachings of the presentinvention. For example, rather than circular openings, cutouts 50 maycomprise square, rectangular, triangular, oval, semi-circular, diamondshaped, or practically any other geometric configuration and stillobtain some or all of the benefits described herein. Cutouts 50 arepositioned, shaped, and sized such that support post 34 retainssufficiently high strength in the lateral direction (the directionperpendicular to the guardrail beam 12) to capture and redirect animpacting vehicle with reasonable dynamic deflection.

The horizontal location of cutouts 50 within flanges 36 and 38 may alsobe altered significantly, within the teachings of the present invention.In the illustrated embodiment of FIGS. 2A-2C, cutouts 50 are locatedapproximately twenty millimeters (0.79 inches) from outer edges offlanges 36 and 38. However, in alternative embodiments, cutouts 50 maybe located closer to such edges or further from such edges. In oneembodiment, cutouts 50 may be configured such that they extend all theway to the edge of the flange such that there is a break in materialbeginning at the edge. In this manner, a traditional punch could beemployed at the edge to form a semi-circular opening that extends to theedge of the flange.

Alternatively, a sawcut, diamond shaped notch, or other notch or cutcould be employed from the outer edge of the flange and extended inwardto form cutouts 50. In this manner, the sawcut, diamond shaped notch, orother notch or cut would form the starting point of the likely point ofyielding along the weak axis of the support post. Rather than a sawcut,a similar configuration may include a slot in which the longestdimension extends horizontally through the flange. Such a slot may beginor terminate at the edge of the flange or otherwise be disposedcompletely within the material of the flange.

FIGS. 3A-3C illustrate a support post 70, in accordance with anotherembodiment of the present invention. Support post 70 is a W8×10 Wideflange and is therefore slightly larger and heavier than the W6×8.5 Wideflange of FIGS. 2A-2C. In particular embodiments, the W8×10, such asthat illustrated in FIGS. 3A-3C, may be particularly well suited forinstallation as a support post 34 in terminal portion 16 of guardrailsystem 10. Additionally or alternatively, support post 70 may be usedwhen additional strong axis strength is desired to, for example, reducedeflection of guardrail system 10 while sufficiently reducing thestrength of the post about the weak axis to maintain vehicle contactforces and damage at acceptable levels.

Support post 70 is very similar in configuration to support post 34,although many of the dimensions of relative aspects and components areslightly different. Therefore, support post 70 will not be described insignificant detail. Cutouts 72 of support post 70 are slightly largerthan cutouts 50 of FIGS. 2A-2C. In the illustrated embodiment of FIGS.3A-3C, cutouts 72 are approximately twenty-one millimeters in diameter.It is generally recognized, however, that the provided dimensions ofcutouts 72 and bolt holes 74 are provided for example purposes only;cutouts 72 and bolt holes 74 may be of any appropriate size. It isanticipated that the diameter of cutouts 72 may vary betweenapproximately 13 and 21 millimeters, in various embodiments. Where as inthe illustrated configuration cutouts 72 are the same size as bolt holes74, fabrication of support post 70 is simplified since the same toolsthat are used to punch bolt holes 74 may be used to punch cutouts 72.Tooling costs are thereby reduced since the tools need only bere-indexed to provide additional holes for cutouts 72.

FIGS. 4A-4C illustrate a support post 100, in accordance with anotherembodiment of the present invention. In the illustrated embodiment,support post 100 is a W6×8.5 Wide Flange configured such that supportpost 100 may be particularly well suited for installation as a LONsupport post 14 b in LON portion 18 of guardrail system 10. Accordingly,support post 100 may also be described herein as “LON support post 100.”LON support post 100 is very similar in configuration to support post34, although many of the dimensions of relative aspects and componentsare slightly different. The illustrated embodiment may provide optionalweakening about the weak axis without appreciably affecting the strongaxis strength of the post. It is also one of the most economicalembodiments for achieving satisfactory impact performance of guardrailsystem 10.

As shown in FIGS. 4A-4C, LON support post 100, which supports aguardrail beam, such as guardrail beam 12, has a length of approximately1.8 m (6 ft). When incorporated into a guardrail system, such asguardrail system 10, multiple LON support posts 100 may be spacedapproximately 1.9 m (6 ft-3 inches) on center, in a particularembodiment. Although bolt holes 110 are depicted as maintaining thecenter of the guardrail beam at a distance that is on the order of 635millimeters (25 inches) above grade, it is generally recognized that theillustrated dimensions are for example purposes only; the number, size,location, and configuration of boltholes 48 may be significantlymodified within the teachings of the present invention. In variousembodiments, it is anticipated that bolt holes 110 may maintain thecenter of the guardrail beam at a distance that is between 550 and 750millimeters (1.8-2.5 feet) above grade.

Similar to the support posts described above, LON support post 100 hasadequate strength in the lateral direction and sufficiently low strengthin the longitudinal direction. LON support post 100 may be embedded inthe ground, a concrete footing, or a metal socket. LON support post 100may be made of wood, metal, plastic, composite materials, or anycombination of these or other suitable materials. Furthermore, thecross-section of LON support post 100 may be any engineered shapesuitable for releasably supporting a guardrail beam, such as guardrailbeam 12. Such cross-sectional shapes may include, but are not limitedto, square, rectangular, round, elliptical, trapezoidal, solid, hollow,closed, or open.

Similar to previously described embodiments, LON support post 100includes a weakened section, such as cutouts 108, that provide reducedstrength in the longitudinal direction but maintained strength in thelateral direction. The weakened section may include one or more openingsin the form of round or elliptical holes, notches, vertical slots,horizontal slots, saw cuts, or any combination of these or otheropenings. Alternatively, a sawcut, diamond shaped notch, or other notchor cut could be employed from the outer edge of the flange and extendedinward to form cutouts 50. As discussed above, the weakened section isgenerally at ground level such that LON support post 100 will yield atground level but may vary above or below grade. The opening or otherweakened section may be located on the interior of the post or mayintersect an exterior edge. The geometry and size of the opening is asis required for a given post cross section such that the force requiredto fail, fracture, or yield the post about its strong axis is reducedsuch that the magnitude and severity of vehicle contact or snaggingforces are reduced to safe levels that mitigate the potential foroccupant injury and vehicle instability. Where the weakened sectionincludes one or more sawcuts, diamond shaped notches, or other notchesor cuts, the weakened section may be cut into the side of the post inone embodiment. Where the weakened section includes a slot, the slot mayinclude a sharp or rounded edge bottom.

As shown in FIG. 4A, the weakened section includes cutouts 108 ofsupport post 100, which are approximately 21 millimeters ( 13/16 of aninch) in the illustrated embodiment. Like support post 70, cutouts 108are the same size as boltholes 110 in this configuration. Accordingly,fabrication of LON support post 100 is simplified since the same toolsthat are used to punch bolt holes 110 may be used to punch cutouts 108.Tooling costs are thereby reduced since the tools need only bere-indexed to provide additional holes for cutouts 108. It is generallyrecognized, however, that the provided dimensions of cutouts 72 and boltholes 74 are provided for example purposes only; cutouts 72 and boltholes 74 may be of any appropriate size. It is anticipated that thediameter of cutouts 72 may vary between approximately 13 and 21millimeters, in various embodiments.

FIGS. 5A-5C illustrates a LON support post 180, in accordance with analternative embodiment of the present invention. LON support post 180 isa W8×10 Wide flange and is, therefore, larger and heavier than theW6×8.5 Wide flange of FIGS. 4A-4C. LON support post 180 is very similarin configuration to previously described support posts, although many ofthe dimensions of relative aspects and components may be slightlydifferent. For example, cutouts 182 of LON support post 180 areapproximately 13 millimeters (½ inch) in diameter. In thisconfiguration, cutouts 182 are slightly smaller than bolt holes 184,which are approximately 21 millimeters (0.82 inches) in diameter. It isgenerally recognized, however, that the provided dimensions of cutouts182 and bolt holes 184 are provided for example purposes only; cutouts182 and bolt holes 184 may be of any appropriate size. Like theembodiments described above, it is anticipated that the diameter ofcutouts 182 may vary between approximately 13 and 21 millimeters, invarious embodiments.

FIGS. 6A-6C illustrate a LON support post 186, in accordance with analternative embodiment of the present invention. As illustrated, LONsupport post 186 is a 6×8 wood post. Thus, LON support post 186 has anominal width of approximately 6 inches and a nominal depth ofapproximately 8 inches. Although formed of wood, it is anticipated thatsupport post 186 may be particularly well suited for installation as aLON support post 14 b in LON portion 18 of guardrail system 10. Theillustrated embodiment may provide optional weakening about the weakaxis without appreciably affecting the strong axis strength of the post.

As shown in FIGS. 6A and 6B, LON support post 186, which supports aguardrail beam, such as guardrail beam 12, has a length of approximately1830 mm (6 ft). Bolt holes 188 have a diameter on the order ofapproximately 13/16 of an inch. Although bolt holes 188 are depicted asmaintaining the center of the guardrail beam at a distance that is onthe order of 550 millimeters (21 inches) above grade, it is generallyrecognized that the illustrated dimensions are for example purposesonly; the number, size, location, and configuration of bolt holes 188may be significantly modified within the teachings of the presentinvention. In various embodiments, it is anticipated that bolt holes 188may maintain the center of the guardrail beam at a distance that isbetween 550 and 750 millimeters (1.8-2.5 feet) above grade.

LON support post 186 is formed of wood, plastic, or a composite materialand may be embedded in the ground, a concrete footing, a metal socket,or a foundation tube. Although illustrated as having a 6×8 rectangularshape, the cross-section of LON support post 186 may be any engineeredshape suitable for releasably supporting a guardrail beam, such asguardrail beam 12. Such cross-sectional shapes may include, but are notlimited to, square, rectangular, round, elliptical, trapezoidal, solid,hollow, closed, or open.

Similar to the support posts described above, LON support post 186 hasadequate strength in the lateral direction and sufficiently low strengthin the longitudinal direction. Specifically, LON support post 186includes a weakened section, such as a cutout 190, that provide reducedstrength in the longitudinal direction but maintained strength in thelateral direction. As shown in FIGS. 6A-6C, cutout 190 of support post186 is of a circular shape and has a diameter on the order ofapproximately 89 millimeters (3.5 inches). It is generally recognized,however, that the provided dimensions of cutout 190 is provided forexample purposes only. Further, the weakened section may include one ormore openings in the form of round or elliptical holes, semi-circularopenings, diamond notches, notches, vertical slots, horizontal slots,saw cuts, or any combination of these or other openings.

As discussed above, the weakened section is generally at ground levelsuch that LON support post 186 will yield at ground level, but may varyabove or below grade. The opening or other weakened section may belocated on the interior of the post or may intersect an exterior edge.The geometry and size of the opening is as is required for a given postcross section such that the force required to fail, fracture, or yieldthe post about its strong axis is reduced such that the magnitude andseverity of vehicle contact or snagging forces are reduced to safelevels that mitigate the potential for occupant injury and vehicleinstability. Where the weakened section includes one or more notches,the notches may be cut into the side of the post in one embodiment.Where the weakened section includes a slot, the slot may include a sharpor rounded edge bottom.

In operation, the LON support posts described above in FIGS. 4A-4C,5A-5C, and 6A-6C are connected to the guardrail beam such that uponimpact, the connection between the LON support posts and guardrail beamwill yield in preferred embodiments. Because the LON support postsinclude weakening cutouts at approximately the ground elevation, the LONsupport posts may bend at the weakened section upon vehicular impact.Despite the deflection of LON support posts upon impact, however, theguardrail beam may remain at the originally designed elevation. As aresult, the guardrail beam may substantially prevent an errant vehiclefrom running over the guardrail beam and/or becoming unstable.

Many advantages may be realized by the use of modified, engineered LONsupport posts of FIGS. 4A-4C, 5A-5C, and 6A-6B. First, use of modified,engineered posts in the standard LON or non-terminal portion of theguardrail system mitigates the severity of the interaction (snagging)between an impacting vehicle and the post without changing thedeflection characteristics of the guardrail system. Second, because theLON support posts release from the guardrail beam, the flanges of theLON support posts may be prevented from tearing the guardrail beam. As aresult, offset blocks (spacers placed between the flanges of the LONsupport post and the guardrail beam) may be reduced in size or removedaltogether, which can provide benefits in terms of space and costsavings.

Other modifications to support posts and LON support posts inparticular, may further prevent tearing of the guardrail beam uponimpact. For example, FIG. 7 illustrates a support post 200 that includesa modified flange for the further protection of the guardrail beam. Itis generally recognized that support post 200 may include a terminalsupport post 14 a or a LON support post 14 b. In the illustratedembodiment, support post 200 includes an elongate, continuous structuralmember of a modified Wide flange configuration. Similar to the supportposts described above, support post 200 includes two flanges 202 and 204that are coupled at their respective midpoints by a web 206. Flanges 202and 204 at their respective midpoints are generally parallel with oneanother and in a spaced relation.

With regard to the modified Wide flange shape used as support post 200,the cross section of support post 200 is shaped like a modified letter“H” or a modified letter “I”. Specifically, a first flange 202 issubstantially straight and, thus, forms a standard leg of an “H” or “I”.A second flange 204 includes a substantially rounded surface such that afirst edge 210 and a second end 212 of second flange 204 is curvedinward toward web 206 and first flange 202. Second flange 204 forms theface of the support post 200 that couples to and lies adjacent to aguardrail beam 208.

In particular embodiments, second flange 204 may slightly longer thanfirst flange 202. For example, in a particular embodiment, support post200 is formed from a modified W6×8.5. Whereas a standard W6×8.5 membermay include two flanges that are each approximately four inches long,second flange 204 is slightly longer than the standard flange and, thus,slightly longer than first flange 202. For example, in a particularembodiment, second flange 204 may have a length that is approximatelysix inches long.

In operation, because second flange 204 is rounded toward first flange202, no sharp edges of support post 200 are adjacent to guardrail beam208. As a result, second flange 204 forms a cushion at the interfacebetween guardrail beam 208 and support post 200. Accordingly, guardrailbeam 208 is not susceptible to rupture by the sharp edges of supportpost 200 when an errant vehicle comes into contact with the supportpost-guardrail beam combination.

Despite some structural and orientation differences discussed above,flanges 202 and 204 of support post 200 may include, in particularembodiments, a weakened section such that, similar to the support postsdiscussed above, modified support post 200 includes a relatively “weak”axis W and a relatively “strong” axis S. For the reasons describedabove, modified support post 200 is normally installed along a roadwaysuch that weak axis W is generally perpendicular to the direction oftraffic, and strong axis S is generally parallel to the direction oftraffic. Accordingly, modified support post 200 is typically able towithstand a significant impact (e.g., with a car traveling at a highrate of speed) about the strong axis S without substantial failure.However, modified support post 200 is intentionally designed such thatyielding will more readily occur in response to an impact about the weakaxis W.

The modification of the support post to include a curved flange as shownin FIG. 7 is merely one method of protecting a guardrail beam frompotential tearing by the support post. Previous methods for preventingthe rupturing of the guardrail beam by the sharp edges of the supportpost flanges include the positioning an offset block between the flangeof support post 14 and guardrail beam 12. Recent trends in guardrailsystems include increasing the depth of offset blocks to prevent postsnagging. When a frangible or yielding post such as support post 14 isused to support the guardrail beam, however, the offset block need onlyprevent contact between the guardrail beam and post flanges.

In the absence of an offset or spacer block, a flange protector may bepositioned at the interface of the guardrail beam and support post. Theflange protector may extend beyond the edges of both the post and therail element to shield the rail element from the edges of the supportpost and, thus, prevent initiation of cuts or tears in the guardrailbeam in the vicinity of the support post as the guardrail system deformsduring an impact. The flange protector may take the form of a platefabricated from metal, wood, plastic, rubber elastomer, or compositematerials. When used in conjunction with a corrugated rail element, suchas a W-beam or thrie beam, the plate may be fabricated to conform to theshape of the rail element such that it can nest inside the rail element.The dimensions of the plate are such that the edges of the plate extendto or beyond the edges of the support post.

FIGS. 8A and 8B illustrate a flange protector 250 for attachment to asupport post 252. Flange protector 250 is a modification of standardoffset blocks and serves to prevent tearing of the guardrail beam duringimpact. Because flange protector 250 is a much smaller spacer thanstandard offset blocks, flange protector 250 may be incorporated into aguardrail system at a lower cost than a standard offset block. Althoughflange protector 250 may be comprised of plastic, in preferredembodiments, it is generally recognized that flange protector 250 may bealternatively made of wood, metal, rubber elastomer, compositematerials, or any combination of these or other suitable materials.

Flange protector 250 includes a body portion that is substantiallyrectangular. In particular embodiments, flange protector 250 maycomprise a substantially flat plate. In other embodiments and in theillustrated embodiment, flange protector 250 includes an indentation 254in the a first surface 256 that is proximate to support post 252 whenthe flange protector 250 and support post 252 are assembled together.Specifically, when assembled together, a flange 258 of support post 252that is proximate flange protector 250 fits into indentation 254.Accordingly, the dimensions of flange protector 250 and the size ofindentation 254 may vary as is appropriate for the particular size andshape of support post 252. It is generally recognized, however, thatindentation 254 is optional, and flange protector 250 may or may notinclude such an indentation.

In various embodiments, the depth of flange protector 250 may beselected based on the depth of support post 252. For example, in aparticular embodiment, the depth of flange protector 250 may be selectedto be less than the predetermined depth of the support post and may beselected to be less than half of the predetermined depth of the supportpost. As another example, the depth of flange protector 252 may beselected to be less than three inches.

In particular embodiments, for example, where support post 252 includesa W6×8.5 Wide flange, flange protector 250 has a length on the order ofapproximately 360 millimeters (14.17 inches) and a width on the order ofapproximately 131 millimeters (5.16 inches). The depth of flangeprotector 250 may vary within a range on the order of approximately 13to 62 millimeters (0.5 to 2.4 inches). Indentation 254 in first surface256 may have a depth of approximately 10 millimeters (0.39 inches), in aparticular embodiment. Thus, lips on either side of flange protector 250may be raised approximately 10 millimeters (0.39 inches) to protect theguardrail beam from the edges of the abutted flange 258 of support post252 and to keep flange protector 250 from rotating once connected tosupport post 252. The width of the lips on either side of indentation254 may be on the order of approximately 13 mm (0.5 inches). Forconnection between support post 252 and the guardrail beam (not shown),flange protector 250 includes one or more boltholes 260 that areapproximately 21 millimeters (0.82 inches) in diameter, in theillustrated embodiment.

The dimensions of flange protector 250 may also be varied. Thecombination of flange protector 250 with the frangibility of supportpost 252 in a LON section of guardrail system 10 may provide enhancedimpact performance and reduced installation cost. Specifically, a flangeprotector 250, as an alternative to the standard offset block, may costmuch less than the cost of a deep offset block and may be attractive toa number of highways and roads agencies where it is anticipated that theomission of both may result in a system with an increased potential forincidence of rupture of the guardrail beam when contacted with flange258 of support post 252.

As described above, flange protector 250 shields the guardrail beam fromthe sharp edges of support post 252 to prevent rupturing of theguardrail beam. Furthermore, a structure such as flange protector 250may be used as a retrofit spacer block when steel-yielding support post252 is placed in a foundation tube as an alternative to a wood post.Thus, anywhere it is desirable to protect the guardrail beam from theflanges of support posts, a flange protector 250 may be used. As anadditional variation, it is recognized that support post may inparticular embodiments include a structural member that of a differentcross-sectional shape than that described. For example, and as discussedabove, support post may comprise a rectangular, a tubular member, or anyother appropriate shape. Where support post does not include flangessuch as flanges 258, it is recognized that flange protector may beselected to accommodate the selected cross-sectional shape of thesupport post and may be termed “a guardrail beam protector.” Returningto FIG. 1, guardrail beam 12 is attached to support posts 14 withconnectors (not shown). The connectors may be threaded or insertedthrough bolt holes formed through support posts 14 and correspondingbolt holes formed through guardrail beam 12. Oversized guardrail nutsmay be used on the back side of the support post 14 flange. Bolt holesformed through support posts 14 were illustrated and described abovewith respect to FIGS. 2A-2C, 3A-3C, 4A-4C, 5A-5C, 6A-6B, and 7 and wereidentified by reference numerals 48, 74, 110, 184, and 188,respectively.

It is desirable for the connectors to sufficiently support guardrailbeam 12 but to be readily released upon load being directly applied tosupport post 14 or upon deflection of the rail element and rotation ofthe support post in surrounding soil. For example, the connectors mayenable support posts 14 to readily release from guardrail beam 12 whensupport post 14 is contacted by a vehicle. FIG. 9 illustrates an exampleof a connector 300 for coupling a guardrail beam 12 with a yieldingsupport post 14, such as a terminal support post 14 a or a LON supportpost 14 b. The configuration of connector 300 is such as to providesufficiently weak connection between guardrail beam 12 and support post14 so that support post 14 detaches from guardrail beam 12 when struckby an errant vehicle. As a result, guardrail beam 12 remainssubstantially at its original height after impact and the errant vehiclemay be prevented from driving over the guardrail beam 12 and furtherleaving the roadway or becoming unstable.

In particular embodiments, connector 300 includes a bolt with a taperedor wedge-shaped head 302, such as a countersunk bolt. Connector 300provides sufficiently low force against guardrail beam 12 to releasesupport post 14 from guardrail beam 12 when an errant vehicle contactsand displaces support post 14. Stated differently, the connection formedbetween guardrail beam 12 and support post 14 by connector 300 is strongin shear and weak in tension. The shape of countersunk head 302 allowsconnector 300 to pull through the mounting slot on the guardrail beam12. Connector 300 may then be displaced with support post 14 uponimpact.

Such a connector is improved over oval shoulder button head bolts thatprovide adequate support for the guardrail beam but do not providesufficiently low release strength. Connector 300 is also improved oversmall diameter bolts, which are typically used with several washers.Small diameter bolt-washer combinations provide only a limited abilityto support the guardrail beam (not strong in shear) and have variablerelease strengths.

In a particular embodiment, connector 300 may include slottedcountersunk bolts such as, for example, 16 mm (⅝-inch) diameter by 38 mm(1-½-inch) long slotted flat countersunk head machine screws. Thecountersunk head 302 of connector 300, in such an embodiment, may have adiameter on the order of approximately 25 millimeters (1 inch) and havea length on the order of 13 millimeters (½ inch). Other embodiments mayinclude a countersunk head 302 having a diameter on the order of 25millimeters (1 inch) and a length on the order of 6.5 millimeters (¼inch). It is generally recognized, however, that these are merely twoexamples of connectors 300 that may be used to releasably engageguardrail beam 12 with support post 14. Other connectors that may beused in place of connector 300 include those specified by ANSI/ASMEB18.5.

Still other, alternative embodiments of possible connectors may includeappropriately sized standard bolts that will tear through the guardrailbeam without rupturing the guardrail beam. For example, the standardbolts may select such that a head portion of the bolt is of a size thatoverlaps an edge of the aperture by a distance that generates a desiredpullout resistance. In particular embodiments, the size of the headportion selected as a function of a thickness of the guardrail beam.Such bolts may include ⅝-inch bolts, ¼-inch bolts, or 3/16-inch boltswith or without washers. A plow bolt may also be used where theresulting connection is weak in tension such as to release when alateral load is applied. In still other embodiments, connector 300 mayrelease through fracture, shear, or tensile failure.

FIGS. 10A-10C illustrate another example of a connector 400 for couplinga guardrail beam 12 with a yielding support post 14, such as a terminalsupport post 14 a or a LON support post 14 b. Like connector 300,connector 400 includes a bolt with a countersunk head 402 to provideadequate support of guardrail beam 12. Connector 400 providessufficiently low force against guardrail beam 12, to release supportpost 14 from guardrail beam 12 when an errant vehicle contacts anddisplaces support post 14. Stated differently, connector 400 forms aconnection between guardrail beam 12 and support post 14 that is strongin shear and weak in tension. The shape of countersunk head 402 allowsconnector 400 to pull through the mounting slot on the guardrail beam12. Connector 400 may then be displaced with support post 14 uponimpact.

Additionally, the configuration of connector 400 prevents connector 400from rotating when connector 400 is used to couple support post 14 withguardrail beam 12. Specifically, head 402 of connector 400 includes afirst surface 404 and a second surface 406. Whereas first surface 404comprises the outer surface of connector 400, second surface 406 isproximate threaded shaft 408. In the illustrated embodiment, firstsurface 404 of head 402 is of a substantially round configuration. Bycontrast, second surface 404 is of a substantially oval configuration.Thus a portion of head 402 includes a shoulder 410. Where guardrail beam12 includes a slotted hole through which connector 400 is placed, theoval shape of shoulder 404 prevents connector 400 from rotating in theslotted hole. The shoulder 410 of connector 400 also limits thehorizontal movement of connector 400 within the slotted hole ofguardrail beam 12. This, in turn, limits the amount of overlap of head402 of connector 400 with the edge of the slotted hole of guardrail beam12. The result is that the pullout force required to disengage connector400 from guardrail beam 12 is further reduced.

In a particular embodiment, connector 400 may include slottedcountersunk bolts such as, for example, 16 mm (⅝-inch) diameter by 38 mm(1-½-inch) slotted flat countersunk head machine screws. The countersunkhead 402 of connector 400, in such an embodiment, may have a diameter onthe order of approximately 25 millimeters (1 inch) and have a length onthe order of 13 millimeters (½ inch). The diameter of the longerdimension of oval shoulder 406 may correspond generally with thediameter of head 402 or approximately 1 inch, and the diameter of theshorter dimension of oval shoulder 406 may correspond generally with thediameter of the bolt shaft or approximately ⅝ inch. It is generallyrecognized, however, that this merely one example of a connectors 400that may be used to releasably engage guardrail beam 12 with supportpost 14. Other connectors may be used in place of connector 400.

Technical advantages of particular embodiments of the present inventioninclude a LON guardrail support post that has sufficient strong axisstrength to redirect vehicles that collide along the length of theguardrail system at an angle to the flow of traffic. As a result, theguardrail system may readily yield to an impacting vehicle at low forcelevels.

A further technical advantage may include a weakened connection betweenthe support post and guardrail beam such that the support post detachesfrom the guardrail beam when struck by an errant vehicle. Specifically,a connector may be provided that adequately supports the guardrail beamwhile releasing from the guardrail beam when a lateral force is appliedto the guardrail beam. Accordingly, in particular embodiments, anadvantage may be that the connection is strong in shear and weak intension.

At least four types of guardrail support members are described andillustrated within this specification: (I) W6×9 Wide flanges; (II) W8×10Wide flanges; (III) W6×8.5 Wide flanges; and (IV) weakened wood posts.It should be recognized by those of ordinary skill in the art thatpractically any size guardrail support post may be enhanced byincorporating the teachings of the present invention. The size, weightand configuration of the support post are just a few factors to beconsidered to determine the appropriate location of cutouts, to allowyielding along the weak axis while maintaining sufficient strength alongthe strong axis to redirect impacting vehicles.

Although the present invention has been described by severalembodiments, various changes and modifications may be suggested to oneskilled in the art. It is intended that the present invention encompasssuch changes and modifications as fall within the scope of the presentappended claims. For example, the features described above may be usedindependently and/or in combination with each other or other designmodifications. Changes in the size or strength of the bolts connectingthe rail to the offset blocks or flange protectors and support posts andthe hole/slot pattern in the rail through which these connecting boltspass may be varied in any manner suitable for enabling the post torelease from the guardrail element.

1. A guardrail safety system, comprising: a guardrail beam; a pluralityof support posts in spaced apart relation to one another, each supportpost configured to be releasably coupled to the guardrail beam; and aplurality of connectors for coupling the plurality of support posts tothe guardrail beam, each connector including a head portion that isconfigured to provide a sufficiently strong connection between theguardrail beam and the support post to support the guardrail beam and asufficiently weak connection between the guardrail beam and the supportpost to enable the support post to detach from the guardrail beam whenstruck by the errant vehicle.
 2. The guardrail safety system of claim 1,wherein each of the plurality of connectors comprise a bolt having acountersunk head defined by a first surface and a second surface, thecountersunk head having a tapered side between the first and secondsurfaces.
 3. The guardrail safety system of claim 2, the countersunkhead includes a shoulder proximate a threaded shaft of the bolt.
 4. Theguardrail safety system of claim 2, wherein each countersunk head of thebolt comprises: a first surface having a substantially roundconfiguration; and a second surface proximate a threaded shaft of thebolt, the second surface having a substantially oval configuration toprevent the connector from rotating relative to the guardrail beam. 5.The guardrail safety system of claim 1, wherein the guardrail beamcomprises a plurality of mounting slots, the guardrail beam coupled toone or more support posts by at least one of the plurality of connectorspassing through an associated slot of the guardrail beam.
 6. Theguardrail safety system of claim 1, wherein each of the plurality ofconnectors comprise: a threaded shaft; a head portion coupled to thethreaded shaft; and a shoulder portion proximate the threaded shaft andconfigured to prevent the connector from rotating relative to theguardrail beam.
 7. The guardrail safety system of claim 1, wherein atleast a portion of the plurality of support posts comprise: a lowerportion for installing below grade adjacent the roadway; a mid portionthat lies substantially adjacent the grade, the mid portion including aweakened section operable to weaken the support post about a first axiswithout substantially changing the behavior of the support post about asecond axis that is generally perpendicular to the first axis; and anupper portion releasably coupled to the LON portion of the guardrailbeam.
 8. The guardrail safety system of claim 7, wherein the weakenedsection is selected from the group consisting of at least one cutoutformed through the support post, at least one cutout formed in a surfaceof the support post, at least one notch formed in a surface of thesupport post, at least one diamond-shaped notch formed in a surface ofthe support post, at least one sawcut formed in a surface of the supportpost, at least one semi-circular opening formed in a surface of thesupport post, at least one semi-circular opening formed through thesupport post, and at least one aperture formed through the support post.9. The guardrail safety system of claim 1, wherein: the support post iscomprised of a material selected from the group consisting of steel,wood, plastic, and composites; and the shape of the support post isselected from the group consisting of an I-beam, an H-beam, a C-channel,an S-beam, a W-beam, a M-beam, a rectangular member, a round member, asquare member, and a tubular member.
 10. The guardrail safety system ofclaim 1, wherein: the guardrail beam includes a plurality of aperturesfor receiving a respective one of the plurality of connectors; eachconnector comprising a head portion of a size that is bigger than theaperture receiving the connector, the head portion overlapping an edgeof the aperture by a distance that generates a desired pulloutresistance, the size of the head portion selected as a function of athickness of the guardrail beam.
 11. A guardrail safety system,comprising: a guardrail beam; a support post coupled to the guardrailbeam, the support post comprising: a lower portion for installing belowgrade adjacent the roadway; a mid portion that lies substantiallyadjacent the grade, the mid portion including a weakened sectionoperable to weaken the support post about a first axis withoutsubstantially changing the behavior of the support post about a secondaxis that is generally perpendicular to the first axis; and an upperportion releasably coupled to the LON portion of the guardrail beam; anda connector for coupling the support post to the guardrail beam, theconnector including a head portion that is configured to provide asufficiently strong connection between the guardrail beam and thesupport post to support the guardrail beam and a sufficiently weakconnection between the guardrail beam and the support post to enable thesupport post to detach from the guardrail beam when struck by the errantvehicle.
 12. The guardrail safety system of claim 11, wherein theconnector comprises a bolt having a countersunk head defined by a firstsurface and a second surface, the countersunk head having a tapered sidebetween the first and second surfaces.
 13. The guardrail safety systemof claim 12, the countersunk head includes a shoulder proximate athreaded shaft of the bolt.
 14. The guardrail safety system of claim 12,wherein each countersunk head of the bolt comprises: a first surfacehaving a substantially round configuration; and a second surfaceproximate a threaded shaft of the bolt, the second surface having asubstantially oval configuration to prevent the connector from rotatingrelative to the guardrail beam.
 15. The guardrail safety system of claim11, wherein the guardrail beam includes a mounting slot, the guardrailbeam coupled to one or more support posts by the connector passingthrough the mounting slot of the guardrail beam.
 16. The guardrailsafety system of claim 11, wherein the connector comprises: a threadedshaft; a head portion coupled to the threaded shaft; and a shoulderportion proximate the threaded shaft and configured to prevent theconnector from rotating relative to the guardrail beam.
 17. Theguardrail safety system of claim 11, wherein the weakened section isselected from the group consisting of at least one cutout formed throughthe support post, at least one cutout formed in a surface of the supportpost, at least one notch formed in a surface of the support post, atleast one diamond-shaped notch formed in a surface of the support post,at least one sawcut formed in a surface of the support post, at leastone semi-circular opening formed in a surface of the support post, atleast one semi-circular opening formed through the support post, and atleast one aperture formed through the support post.
 18. The guardrailsafety system of claim 11, wherein: the support post is comprised of amaterial selected from the group consisting of steel, wood, plastic, andcomposites; and the shape of the support post is selected from the groupconsisting of an I-beam, an H-beam, a C-channel, an S-beam, a W-beam, aM-beam, a rectangular member, a round member, a square member, and atubular member.
 19. The guardrail safety system of claim 11, wherein:the guardrail beam includes an aperture for receiving the connector; theconnector comprising a head portion of a size that is bigger than theaperture receiving the connector, the head portion overlapping an edgeof the aperture by a distance that generates a desired pulloutresistance, the size of the head portion selected as a function of athickness of the guardrail beam.
 20. A guardrail safety system,comprising: a guardrail beam; a plurality of support posts in spacedapart relation to one another, at least a portion of the support postsconfigured to be releasably coupled to the guardrail beam andcomprising: a lower portion for installing below grade adjacent theroadway; a mid portion that lies substantially adjacent the grade, themid portion including a weakened section operable to weaken the supportpost about a first axis without substantially changing the behavior ofthe support post about a second axis that is generally perpendicular tothe first axis; and an upper portion releasably coupled to the LONportion of the guardrail beam; and a plurality of connectors forcoupling at least a portion of the plurality of support posts to theguardrail beam, each connector comprising a countersunk bolt enablingthe support post to detach from the guardrail beam when struck by theerrant vehicle; and wherein the guardrail beam is coupled to at least aportion of the plurality of support posts by at least one of theplurality of connectors passing through an associated slot of theguardrail beam.